Cummins/Onan — Oil By-Pass Valve Inspection
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan CCK engine
Procedure
- Remove cap screw behind gear cover under governor arm.
- Remove spring and plunger with magnet tool.
- Clean plunger and spring with solvent.
- Reinstall plunger and spring.
- Check plunger diameter 0.3365-0.3380 in (8.55-8.59 mm).
- Check spring free length 2-5/16 in (58.74 mm).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Plunger diameter 0.3365-0.3380 in (8.55-8.59 mm)
- Spring free length 2-5/16 in (58.74 mm)
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.